More Like this

1. Biochar and zero-valent iron sand filtration simultaneously removes contaminants of emerging concern and Escherichia coli from wastewater effluent

   https://doi.org/10.1007/s42773-023-00240-y  

   Zhu, Linyan; Chattopadhyay, Suhana; Elijah Akanbi, Oluwasegun; Lobo, Steven; Panthi, Suraj; Malayil, Leena; Craddock, Hillary A.; Allard, Sarah M.; Sharma, Manan; Kniel, Kalmia E.; et al (July 2023, Biochar)

   Abstract Advanced treated municipal wastewater is an important alternative water source for agricultural irrigation. However, the possible persistence of chemical and microbiological contaminants in these waters raise potential safety concerns with regard to reusing treated wastewater for food crop irrigation. Two low-cost and environmentally-friendly filter media, biochar (BC) and zero-valent iron (ZVI), have attracted great interest in terms of treating reused water. Here, we evaluated the efficacy of BC-, nanosilver-amended biochar- (Ag-BC) and ZVI-sand filters, in reducing contaminants of emerging concern (CECs),Escherichia coli (E. coli)and total bacterial diversity from wastewater effluent. Six experiments were conducted with control quartz sand and sand columns containing BC, Ag-BC, ZVI, BC with ZVI, or Ag-BC with ZVI. After filtration, Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated more than 90% (> 1 log) removal ofE. colifrom wastewater samples, while BC, Ag-BC, BC with ZVI and Ag-BC with ZVI also demonstrated efficient removal of tested CECs. Lower bacterial diversity was also observed after filtration; however, differences were marginally significant. In addition, significantly (p < 0.05) higher bacterial diversity was observed in wastewater samples collected during warmer versus colder months. Leaching of silver ions occurred from Ag-BC columns; however, this was prevented through the addition of ZVI. In conclusion, our data suggest that the BC with ZVI and Ag-BC with ZVI sand filters, which demonstrated more than 99% removal of both CECs andE. coliwithout silver ion release, may be effective, low-cost options for decentralized treatment of reused wastewater. Graphical Abstract 

   more » « less
2. A Probabilistic Extension of Action Language

   https://doi.org/10.1017/S1471068418000303  

   LEE, JOOHYUNG; WANG, YI (July 2018, Theory and Practice of Logic Programming)

   Abstract We present a probabilistic extension of action language $${\cal BC}$$+$$ . Just like $${\cal BC}$$+$$ is defined as a high-level notation of answer set programs for describing transition systems, the proposed language, which we call p $${\cal BC}$$+$$ , is defined as a high-level notation of LP MLN programs—a probabilistic extension of answer set programs. We show how probabilistic reasoning about transition systems, such as prediction, postdiction, and planning problems, as well as probabilistic diagnosis for dynamic domains, can be modeled in p $${\cal BC}$$+$$ and computed using an implementation of LP MLN . 

   more » « less
3. Influence of cloud microphysical processes on black carbon wet removal, global distributions, and radiative forcing

   https://doi.org/10.5194/acp-19-1587-2019  

   Xu, Jiayu; Zhang, Jiachen; Liu, Junfeng; Yi, Kan; Xiang, Songlin; Hu, Xiurong; Wang, Yuqing; Tao, Shu; Ban-Weiss, George (January 2019, Atmospheric Chemistry and Physics)

   Abstract. Parameterizations that impact wet removal of black carbon (BC)remain uncertain in global climate models. In this study, we enhance thedefault wet deposition scheme for BC in the Community Earth System Model (CESM)to (a) add relevant physical processes that were not resolved in thedefault model and (b) facilitate understanding of the relative importanceof various cloud processes on BC distributions. We find that the enhancedscheme greatly improves model performance against HIPPO observationsrelative to the default scheme. We find that convection scavenging, aerosolactivation, ice nucleation, evaporation of rain or snow, and below-cloudscavenging dominate wet deposition of BC. BC conversion rates for processesrelated to in-cloud water–ice conversion (i.e., riming, the Bergeronprocess, and evaporation of cloud water sedimentation) are relativelysmaller, but have large seasonal variations. We also conduct sensitivitysimulations that turn off each cloud process one at a time to quantify theinfluence of cloud processes on BC distributions and radiative forcing.Convective scavenging is found to have the largest impact onBC concentrations at mid-altitudes over the tropics and even globally. Inaddition, BC is sensitive to all cloud processes over the NorthernHemisphere at high latitudes. As for BC vertical distributions, convectivescavenging greatly influences BC fractions at different altitudes.Suppressing BC droplet activation in clouds mainly decreases the fraction ofcolumn BC below 5 km, whereas suppressing BC ice nucleation increases thatabove 10 km. During wintertime, the Bergeron process also significantlyincreases BC concentrations at lower altitudes over the Arctic. Oursimulation yields a global BC burden of 85 Gg; corresponding directradiative forcing (DRF) of BC estimated using the Parallel Offline RadiativeTransfer (PORT) is 0.13 W m−2, much lower than previous studies. Therange of DRF derived from sensitivity simulations is large, 0.09–0.33 W m−2,corresponding to BC burdens varying from 73 to 151 Gg. Due todifferences in BC vertical distributions among each sensitivity simulation,fractional changes in DRF (relative to the baseline simulation) are alwayshigher than fractional changes in BC burdens; this occurs because relocating BCin the vertical influences the radiative forcing per BC mass. Our resultshighlight the influences of cloud microphysical processes on BC concentrationsand radiative forcing. 

   more » « less
4. Thermal conductivity of hexagonal BC ₂ P – a first-principles study

   https://doi.org/10.1039/d0ra08444a  

   Muthaiah, Rajmohan; Tarannum, Fatema; Annam, Roshan Sameer; Nayal, Avinash Singh; Danayat, Swapneel; Garg, Jivtesh (November 2020, RSC Advances)

   null (Ed.)

   In this work, we report a high thermal conductivity ( k ) of 162 W m −1 K −1 and 52 W m −1 K −1 at room temperature, along the directions perpendicular and parallel to the c -axis, respectively, of bulk hexagonal BC 2 P (h-BC 2 P), using first-principles calculations. We systematically investigate elastic constants, phonon group velocities, phonon linewidths and mode thermal conductivity contributions of transverse acoustic (TA), longitudinal acoustic (LA) and optical phonons. Interestingly, optical phonons are found to make a large contribution of 30.1% to the overall k along a direction perpendicular to the c -axis at 300 K. BC 2 P is also found to exhibit high thermal conductivity at nanometer length scales. At 300 K, a high k value of ∼47 W m −1 K −1 is computed for h-BC 2 P at a nanometer length scale of 50 nm, providing avenues for achieving efficient nanoscale heat transfer. 

   more » « less
5. Contribution of biomass burning to black carbon deposition on Andean glaciers: consequences for radiative forcing

   https://doi.org/10.1088/1748-9326/acb371  

   Bonilla, E. X.; Mickley, L. J.; Beaudon, E. G.; Thompson, L. G.; Rodriguez, W. E.; Encarnación, R. Cruz; Whicker, C. A.; Flanner, M. G.; Schmitt, C. G.; Ginot, P. (February 2023, Environmental Research Letters)

   Abstract Andean glaciers have melted rapidly since the 1960s. While some melting is likely due to anthropogenic climate change driven by increasing greenhouse gases, deposition of light-absorbing particles such as black carbon (BC) may also play a role. We hypothesize that BC from fires in the Amazon Basin and elsewhere may be deposited on Andean glaciers, reducing the surface albedo and inducing further melting. Here we investigate the role of BC deposition on albedo changes in the Andes for 2014–2019 by combining atmospheric chemistry modeling with observations of BC in snow or ice at four mountain sites in Peru (Quelccaya, Huascarán, Yanapaccha, and Shallap) and at one site in Bolivia (Illimani). We find that annual mean ice BC concentrations simulated by the chemical transport model GEOS-Chem for 2014–2019 are roughly consistent with those observed at the site with the longest record, Huascarán, with overestimates of 15%–40%. Smoke from fires account for 20%–70% of total wet and dry deposition fluxes, depending on the site. The rest of BC deposited comes from fossil fuel combustion. Using a snow albedo model, we find that the annual mean radiative forcing from the deposition of smoke BC alone on snow ranges from +0.1 to +3.2 W m⁻²under clear-sky conditions, with corresponding average albedo reductions of 0.04%–1.1%. These ranges are dependent on site and snow grain size. This result implies a potentially significant climate impact of biomass burning in the Amazon on radiative forcing in the Andes. 

   more » « less